Fix:zk too many tcp conn

[wenxuwan]

Now every registry have one connection with zk, this is a waste of resources. It is completely unnecessary for dubbo-go to maintain a complex reconnection mechanism, which will increase the number of links and memory of zk.

[cityiron]

If you change, ignore

[jack15083]

ignore

[codecov-io]

Codecov Report

Merging #1010 (9d8c910) into 1.5 (968650f) will decrease coverage by 0.24%.
The diff coverage is 60.80%.

@@            Coverage Diff             @@
##              1.5    #1010      +/-   ##
==========================================
- Coverage   59.53%   59.28%   -0.25%     
==========================================
  Files         259      268       +9     
  Lines       12737    13016     +279     
==========================================
+ Hits         7583     7717     +134     
- Misses       4199     4336     +137     
- Partials      955      963       +8     

Impacted Files	Coverage Δ
cluster/cluster_impl/available_cluster.go	100.00% <ø> (ø)
cluster/cluster_impl/zone_aware_cluster_invoker.go	64.28% <ø> (ø)
cluster/router/healthcheck/factory.go	66.66% <0.00%> (ø)
cluster/router/tag/router_rule.go	89.47% <ø> (+12.20%)	⬆️
common/config/environment.go	51.72% <ø> (ø)
common/extension/config_post_processor.go	0.00% <0.00%> (ø)
common/extension/conn_checker.go	0.00% <0.00%> (ø)
common/extension/metadata_service.go	0.00% <0.00%> (ø)
common/proxy/proxy_factory/default.go	13.55% <0.00%> (+0.22%)	⬆️
config/base_config.go	64.02% <ø> (ø)
... and 170 more

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[AlexStocks]

pls change the target branch to 1.5